A polycarbonate resin is generally produced using bisphenols as a monomer ingredient and by making use of its superiority such as transparency, heat resistance and mechanical strength, is widely utilized as a so-called engineering plastic in the fields of electric•electronic component, automotive component, optical recording medium and optics such as lens. However, in the application as an optically compensatory film of a flat panel display and the like which are rapidly spreading in recent years, higher optical characteristics such as low birefringence and low photoelastic coefficient are further required, and existing aromatic polycarbonate resins cannot meet the requirement. Also, the conventional polycarbonate resin is produced using a raw material derived from petroleum resources, but in recent years, depletion of petroleum resources is feared, and it is demanded to provide a polycarbonate resin using a raw material obtained from biomass resources such as plant. In addition, because of a concern that global warming due to increase or accumulation of carbon dioxide emissions may bring about climate change or the like, it is demanded to develop a polycarbonate using a plant-derived monomer as a raw material and being carbon neutral even when discarded after use.
Under these circumstances, a method using a special dihydroxy compound as a monomer ingredient, where a polycarbonate resin is obtained while subjecting a monohydroxy compound produced as a by-product by transesterification with a carbonic acid diester to removal by distillation under reduced pressure, has been proposed (see, for example, Patent Documents 1 to 3).
However, such a dihydroxy compound having a special structure is poor in the thermal stability, and its use as a raw material of a polycarbonate resin has a problem that the polymerization reactivity is reduced or coloration due to heat history at the preparation of a raw material or during polymerization occurs to impair the commercial value of the obtained polycarbonate resin. In particular, when it is intended to produce a polycarbonate resin in an industrial scale, a raw material must be kept under heating for a certain time period, and poor thermal stability of the raw material works out to a serious problem.
In order to solve this problem, there is disclosed a method of specifying the amount of impurities in the polycarbonate resin (for example, Patent Document 4) or adding a heat stabilizer to the polycarbonate resin (for example, Patent Document 5).
On the other hand, a method of adding a basic stability improver to a distillatively purified dihydroxy compound is disclosed (for example, Patent Document 6). Furthermore, a method of adding a basic metal salt as a stabilizer to a dihydroxy compound and using the product after distillative purification is disclosed (Patent Document 7).